This project assesses the effects of chronic behavioral stress on lipids, lipoproteins, and apolipoproteins in a healthy male, normolipidemic population. It tests several pathways of model proposing that chronic behavioral stress has this effect (a) because of alterations in health behaviors, such as physical activity, body weight, diet and nutritional factors; (b) because of direct effects of stress on lipids; and (c) most notably in a particularly sensitive subset of individuals. To test this model, this project will utilize a chronic occupational stressor, acute laboratory challenges, behavioral assessment, and a dietary challenge. In addition, it will employ state-of-the-art methods of measuring behavioral changes, such as diet, body weight, and physical activity patterns. The project will utilize a sample of health middle-aged males who are known to predictably experience both high and low degrees chronic occupational stress. Subjects will each participate in three health behavior assessments, scheduled during a period of low chronic occupational stress, followed by one of high chronic occupational stress, and concluding With a period of low chronic occupation stress. During these sessions, information regarding physical activity, dietary intake, body weight and several other health behaviors will be collected. The final session will conclude with a laboratory session designed to psychologically and physically challenge the participants, while lipids, lipoproteins, and apolipoproteins are being assessed. Statistical analyses are hypothesis-driven and designed to specifically test several pathways of the proposed model.